Field of the Invention
This invention relates to a constant velocity ratio universal joint, comprising:
a hollow outer joint member, having an internal surface provided with grooves extending in meridian planes about the axis of the member;
an inner joint member disposed within the outer joint member, and having an external surface having grooves extending in meridian planes about the axis of the inner joint member, facing the grooves in the outer joint member in pairs;
a plurality of balls disposed one in each facing pair of said grooves, for torque transmission between the joint members;
the grooves of each pair diverging from one another towards one end of the joint, and the bases of the grooves in each member being of non-undercut configuration considered from said end of the joint;
and a cage of annular configuration disposed between the outer and inner joint members and having windows wherein the balls are guided.
In joints as above set forth, it is usual to provide the cage with external and internal part-spherical surfaces, which are guided respectively on the internal and external surfaces of the outer and inner joint members between the grooves thereof. Such joints have the disadvantage in that extremely accurate production is necessary in order to achieve the required guidance of the cage. Inaccuracy can lead to the joints having a self-generated resistance to articulation, tending to "catch" or become jammed, so that a higher force has to be applied to the joint to cause it to articulate, especially starting from the aligned (non-articulated) condition.